|Micrograph of a spleen with hyaloserositis. H&E stain.|
|Classification and external resources|
Enlargement of the spleen is known as splenomegaly. It may be caused by sickle cell anemia, sarcoidosis, malaria, bacterial endocarditis, leukemia, pernicious anemia, Gaucher's disease, leishmaniasis, Hodgkin's disease, Banti's disease, hereditary spherocytosis, cysts, glandular fever (mononucleosis or 'Mono' caused by the Epstein-Barr Virus), and tumours. Primary tumors of the spleen include hemangiomas and hemangiosarcomas. Marked splenomegaly may result in the spleen occupying a large portion of the left side of the abdomen.
The spleen is the largest collection of lymphoid tissue in the body. It is normally palpable in preterm infants, in 30% of normal, full-term neonates, and in 5% to 10% of infants and toddlers. A spleen easily palpable below the costal margin in any child over the age of 3–4 years should be considered abnormal until proven otherwise.
Splenomegaly can result from antigenic stimulation (e.g., infection), obstruction of blood flow (e.g., portal vein obstruction), underlying functional abnormality (e.g., hemolytic anemia), or infiltration (e.g., leukemia or storage disease, such as Gaucher's disease). The most common cause of acute splenomegaly in children is viral infection, which is transient and usually moderate. Basic work-up for acute splenomegaly includes a complete blood count with differential, platelet count, and reticulocyte and atypical lymphocyte counts to exclude hemolytic anemia and leukemia. Assessment of IgM antibodies to viral capsid antigen (a rising titer) is indicated to confirm Epstein-Barr virus or cytomegalovirus. Other infections should be excluded if these tests are negative.
Asplenia is the absence of normal spleen function. It predisposes to some septicemia infections. Therefore, vaccination and antibiotic measures are essential in such cases. There are multiple causes:
- Some people congenitally completely lack a spleen, although this is rare.
- Sickle-cell disease can cause a functional asplenia (or autosplenectomy) by causing infarctions of the spleen during repeated sickle-cell crises.
- It may be removed surgically (known as a splenectomy), but this is rarely performed, as it carries a high risk of infection and other adverse effects. Indications include following abdominal injuries with rupture and hemorrhage of the spleen, or in the treatment of certain blood diseases (Idiopathic thrombocytopenic purpura, hereditary spherocytosis, etc.), certain forms of lymphoma or for the removal of splenic tumors or cysts.